OUTLINE: This is a dose-escalation study. Patients are stratified according to prior nitrosourea-based chemotherapy (yes vs no). Patients receive carboplatin IV over 30 minutes on day 1 and oral temozolomide once daily on days 1-5. Treatment repeats every 28 days for a maximum of 6 courses in the absence of disease progression or unacceptable toxicity. Patients with a persistent response may continue to receive temozolomide only for an additional 6 courses. Cohorts of 3-6 patients receive escalating doses of carboplatin and temozolomide until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, additional patients are accrued to receive carboplatin and temozolomide at the recommended phase II dose.